When David Blaine fasted for 44 days in London in 2003 he was pelted with rotten eggs by people who found the stunt distasteful. Hunger artists - men and women who starved themselves in public - amused crowds in Europe as late as the 1920s, but as Sharman Apt Russell explains in this fascinating study, our attitude to hunger has changed. In 1984 Michael Buerk's landmark BBC report brought disturbing images of starving Ethiopians into the nation's living rooms, prompting a massive popular response. The IRA hunger strike in 1981 led to the death of 27-year-old Bobby Sands, who lasted for 66 days. In this context, watching Blaine fast for entertainment struck many observers as obscene.

"You cannot live without hunger," says Russell. "You cannot live with hunger. Hunger begins your exchange with the world." To break bread with our companions is to share in what the psychologist Kurt Lewin called a feeling of "group belongingness"; so refusing to eat - the suffragettes left untouched the meals laid out for them by their jailors - is to refuse to belong. In Kafka's A Hunger Artist (1922), the dying artist, asked to explain himself, simply says: "I couldn't find the food I liked" - a fine summation of Kafka's ingrained resistance to life's contract.

"A hungry body exists as a potent critique of the society in which it exists," noted the anthropologist Nancy Scheper-Hughes, so when food is rejected it upsets people, especially those in authority. Hunger strikers hope to exploit this peculiar dynamic to their advantage. "As the body grows weaker, the power of authority can strangely weaken too," observes Russell. One of the most successful proponents of this method of protest was Gandhi, who took part in no fewer than 17 hunger strikes, the last when he was 78.

"Not eating seems to be innately religious," says Russell, and every major religion equates fasting with sanctity, hunger being akin to chastity. Muslims have Ramadan, Jews Yom Kippur and Catholics Ash Wednesday and Lent. According to Russell, fasting became something of "a female speciality" in Christian history: Catherine of Siena ate only a handful of herbs every day, while Saint Veronica allowed herself five orange pips on Fridays, symbolic of the wounds of Christ. Russell ingeniously links this kind of religious anorexia mirabilis with modern-day anorexia nervosa. "The fasting maid is no longer a miracle," she writes, but "she is still a mystery."

It seems a little hunger can be good for us and Russell explores the subject of fasting for health in some detail in this wide-ranging book, which also takes in the Irish famine, the Warsaw ghetto, wartime starvation experiments and the way famine is reported in the west, particularly the use of images of children. She is also good on the physiology of hunger, revealing precisely what happens when we stop eating - right up to the moment when the body begins to consume itself. This rather grim subject comes to seem profound, thanks to Russell's ruminative prose style and keen intelligence.

Russell tried fasting for this book, but gave up after four days. It wasn't the food she missed, it was "the meaning behind food ... We stitch the day together with flavours and rewards, the gold star of chocolate, lunch with a friend. Not eating made me see that more clearly."